Certain vehicles today, for example including certain diesel-fuel vehicles, utilize a selective catalytic reduction (SCR) unit that is coupled, directly or indirectly, to an engine of the vehicle to reduce nitrogen oxides in the exhaust. SCR units generally convert nitrogen oxides (also commonly referred to as NOx) to nitrogen and water, with the assistance of ammonia or urea solution that is injected into the SCR unit. The amount of ammonia or urea solution that is injected is based on a measured amount of nitrogen oxide.
However, nitrogen oxide sensors may have cross sensitivity with ammonia, which may result in difficulty in accurately measuring nitrogen oxide concentration.
Accordingly, it is desirable to provide methods and systems for improved estimation of nitrogen oxide values for vehicles. It is also desirable to provide methods, systems, and vehicles incorporating such techniques. Furthermore, other desirable features and characteristics of the present invention will be apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.